Super capacitors use aqueous or organic electrolytes. The organic electrolyte system has wider potential window than that of an aqueous electrolyte system. A schematic circuit diagram of a conventional super capacitor using aqueous electrolyte (e.g. an electric double layer capacitor, EDLC) is shown in FIG. 1(a). In FIG. 1(a), the super capacitor is electrically connected to a switch SW and a DC power source VDC, and comprises a first capacitor 11, a second capacitor 12, a separator 13 and an aqueous electrolyte 14. The first capacitor 11 includes a current collector 111 (not shown, see FIG. 1(b)) and a carbon material 112, and the second capacitor 12 includes a current collector 121 (not shown, see FIG. 1(b)) and a carbon material 122. FIG. 1(b) shows another schematic circuit diagram of the conventional super capacitor using aqueous electrolyte. As shown in FIG. 1(b), the super capacitor 1 includes the current collector 111, the carbon material 112, the separator 13, the current collector 121 and the carbon material 122. But, the degeneration and the liquid leakage of the organic-phase electrolyte are easily happened. Thus, solid electrolyte and gel electrolyte are developed to solve the above-mentioned problems. The PEO-based electrolytes commonly exhibit conductivities which range from 10−4 to 10−8 and from 10−4 to 10−3 S cm−1 for solid polymer electrolytes and gel electrolytes, respectively, which are not sufficient to exceed those of the organic electrolytes.
Thus, for increasing the applicability and the conductivity of the gel electrolyte, how to cause the gel electrolyte to include the characteristics of having higher conductivity (e.g., >10−2 S cm−1), lower impedance, higher energy density, higher power density and wider working potential window so as to manufacture this gel copolymer into a thin-film electrolyte to fit in with the usage of a super capacitor is really a problem urgently await to be solved in this field.
Keeping the drawbacks of the prior arts in mind, and employing experiments and research full-heartily and persistently, the applicant finally conceived a super capacitor with gel electrolyte of poly(ethylene glycol) blending poly(acrylonitrile) and manufacturing method thereof.